Container wall



Patented Nov. 26, 1946 Willard 0. Manor, Monroe, Mich., assignor to 1 Consolidated Paper Company, Monroe, Mich., a I

corporation of Michigan No Drawing. Application'S eptember I 7 Serial No. 504,383

This invention relates to shielding, protecting and coating walls, more particularly of fiber-like containers. v

M Thisinvention.hasutility when incorporated in methods of compounding, and applying, and also in ingredients of compositions and their associfor the purpose sought.

ation, especially withreferenceto fiber typesfof containers with an undercoating for a barrier.

between the contents and the wall. The primary course herein is laying of athinfilm, desirably of elastic or stretchable properties having toughness in maintaining askinfupon ,a container wall or undercoating.

The skin andundercoating mayserve as a responsive severing means to effect isolation between the wall andcontents. The container proper may be, in its use, not primarily for refill service. In such latter instances the material may be fiber developed from rag, paper, grass, straw, or wood pulp, and compositions therewith,

in the general class of fiber board, paper board,

box board, and the like. h v

As tothe coatings or coating materials, special value has been developed in features oftoughness orelasticity. In this type of compressible fiber board stock, such is frequently-blanked out and sent in knocked-down shape to be built up into containers. In this blanking, there may be scoring and marking or cutting. Under this inven tion the coating may be applied at or before the blanking operation and be eilicient in the, assembly of the blank into a container even as to the corners where there has been scoring or folding,

The purpose of the coating is to isolate the charged contents ormaterial from attackingthe container. The contents may be hygroscopic, a solvent, vapongrease or oil.

Additional problems arise in the handling of hot substances. The substance to be placed in the containermay have seemingly no afiinity for the container, or be readily fracturable therefrom, asparaffine wax. Again, it may be a substance having tacky or adhesive traits as asphalt. The contents of the container as reposing or solidifying may .or may not tend to hold the. container to shape. Should such contents normally tendnotto hold to shape, the containeradopted hereunder maybe offsuch physical strength in its container walls as to be effective for such holdins Shape- K With 50% starch, as Casava, there may be an equalquantity, or 50% of a film-forming chemi- 2 y h In thisibuildup for the solids of the starch and film-forming plastic, such may be 7# each with say 200# of water. This thin gruel direct Water solution, desirably as a batch, may have a tempering, or water-holding trait or softness characteristic imparted thereto by some 20# of glycerine. ness in achieving this nondrying factor for this tough characteristic may be attained for the plas tic of the coating composition by the use, in lieu of glycerine, of di-ethylene glycol, tri-ethylene glycol, or sulphonated oil, say of the castor typ This proportion of the tempering agent, when in the region of 20# in the 214# proportion suggested, is of commercial economy. However, as there may be longer storage period or other fac-' tors, such as the character of the calendering or facing for the fiber, variation may be adopted.

In fact, as much as 40# of tempering agent or;

plasticizer has been used. I

This composition of starch, plastic andtempering agent, has .but slight absorption properties as to penetration of the fiber board or wall 7 to be coated. It has non-crumbling properties of viscosity as well as retained elasticity efiective as the tempering is a property thereof. In practice, it seems to extend as a very thin film or skin. The extent thereof in applying, whetherby spray,

bruslnidipping o'r'roll coating, may be only just sufficient to'efiect the continuity for. such coating.

.. This film coating continuity is an isolating agent effecting dissipating of attack upon the well due to the contents. In'the instance of. severing from the contents, iwhen 'of a non-tacky nature, altho molten or at a'high temperature as filled into the container, thev coating may t'oa major extent go with the wall, insteadIof adhering with or becoming a part of the contents. In the instance that the contents are edible, these are matters tobe givenattention, However, due to the very thin character of this film, it is of such incredibly minor proportion "as 'to be not in the realm for consideration as an adulterant or contamination of the (container contents when, in

cal. These areinthe fields of resins, or resinlike. materials, andin the cellulose group from polyvinyl alcohol and including methyl cellulose.

In this-compoundin ,referredto asequal quantities, there 'may. be ayariation in the starchy substancespf as-much as one -half, and-;up1to 100%. of the film, forming. material without starch.

The'jtraits to be considered fare'those :of economy.

removal, this film be'associated with such con tents.

E flicient isolation between the container and its contents is achieved by locating this stretchable film on an undercoating. The unde rcoating cooperatesv as a dam or barrier comprising a -dispersion of a powder-like material, preferably very fine andto have it effective in continuity. However, .efficient results in the non-food field have been obtained with fine clays or silicates, such as kaolin. This under-coating is wiped, laid, sprayed or rolled, say in association with Water or a glue agent, and thereby anchored through theaction of this film-carrying overcoating.

Instead of elementally handling engendercoating as merelythe kaolin and thev lueand.

The pliancy or soft-.

water vehicle therefor, supplemental traits of advantage may be achieved in efiicient dispersion thru the medium of a low grade karaya gum of high viscosity. This gum has been used in quantitles and range from to 7#. In fact, instead of this karaya gum, gum arabic or gum tragacanth may answer; but commercially there has been advantage in the karaya type. This advantage arises from its great rate of water solubility. With a charge or quantity of gum, there may be mixed therewith a carbonate. For this solution there may be 150# of water. bonate, when an ammonium bicarbonate, seems among the carbonates to contribute to a greater extent in smoothing out the mix and holding such for a maintained high degree of fluidity. This proportion for the carbonate may be taken as 13%#. At times there are variations in the gum, and this quantity of the carbonate has been increased and decreased as much as 50%.

With this under-coating of viscosity or watercarrying traits established in a degree of stability for smoothness, further advantage arises from incorporating an adhesive therewith. For commercial purposes, a low grade animal glue may be taken, and its proportion may be 13%#, that is, in the quantity adopted for the ammonium bicarbonate. The glue, dissolved in the water, may have its plasticizing traits or properties increased hereunder by the inclusion of say 5 /2# of sodium nitrate therewith. While these proportions for the adhesive, sodium nitrate, glue and water are suggested as 13%# of the glue as to like quantity for the ammonium bicarbonate, such may vary with or away from the carbonate.

Furthermore, in this primary or undercoating, there may be adopted retaining .traits against ready fracture. This tempering or water-carrying or retaining quality, which may even go to the extent of increasing the Water-carrying or mixing values, is attained'thru glycerine, which may be in the quantity of 51 /2#. For such tempering agent, sulphonated oils, of which sulphonated castor oil may be preferred, may be adopted with the quantity in the range of 45#. There may even be variation up and down of 5% or more, as well as with the glycerine.

With this gum dispersed thru the carbonate and nitrate treated adhesive as a vehicle or carrier including the glycerine or tempering agent, there may be introduced the clay or kaolin, 265#, even with an additional 90# of water. The purpose had with this clay is that such may be the filler or body and be of fine particle size or texture. The quantity of water may have its variation for the desired degree of spreadability and be sufficient in the viscosity range for the ingredients, as for dip, spraying, brush painting or roll coating.

Upon pouring a charge of hot material into the container coated with the barrier or dam and having thereon for the film substance a resin, non-adhesive or difiering from the traits of asphalt, the severance may result in approximately all of each of the coatings or residue thereof going with the container.

Example of film coating:

Starch material The car- 7 When an additional or undercoating be desired, such may be thinned with water to the consistency desired for applying.

, The clay powder or under-coating in its nature is porous, as distinguished from the film-forming 'overcoatin-g being impervious. Furthermore, the film-forming overcoating has a property of adherence. The interposition of the powder material undercoating thereby provides a support for the film-forming overcoating and hereunder is desirably sufficient in the proportions to isolate the film-forming overcoating from the wall, due to the continuity of the undercoating.

An instance of practical range for coverage, may betaken as to a container for asphalt. The area for one side, say of a ream of fiber board 24 x 36a total of 2880 sq. ft.may have the clay add to the weight of the board as much In practice this runs around 184%. The fiber board itself varies over quite a range, according to the volume of asphalt. For l0# of asphalt, the container Wall may run .020" to .040", or say from 2201? to 440# per ream. When the container is to carry 400# of asphalt, the fiber board thickness may run .050" to .100", or weigh from 560# to 1120# per ream. The clay undercoating for one side would thus run say 18# to'the ream, whether for the thin or heavier fiber board. The film-forming overcoating would run l# to '2# per ream.

The functioning in all instances is to the end that there is non-adherence and non-contamination between the material of the container and the container walls. In the practice hereunder, even from heat of the contents, the container wall is immune from or resistant to attack by the contents.

The water dispersed clay has such clay run in solids, say from 40% to 60%, in the suspension mixture, with ingredients in solution to provide adhesive properties in body and effectiveness, relatively minor as to the clay, but with the adhesive traits at least just sufficient to establish a bonding mounting for the clay. This is in reality only a temporary characteristic for the bonding or holding action and is possessed as the coating is at first applied. For speed advantage in manufacture, it has been found that this single undercoating has its continuity better established in two applications. These may be in relatively close succession to range for the total clay some 5# per 1000 sq. ft. of surface.

Immediately thereafter, and while this undercoating is still alive in its adherent property; that is, before any crumbling away has occurred; an overcoating is, applied. This overcoating skin or film, in some practice may be complete for the job. However, more efficient results are achieved in association with the major volume undercoating. The traits of this film are continuity against rupture. "Commercial advantages as developed hereunder extend not only to polyvinyl alcohol, but to celluloses or" methyl cellulose type, proteins of casein and mazein types. In getting away from the celluloses by the proteins toward gums,

I as gum arabic and gum tragacanth, the skin-developing body in the starch association brings therewith physical problems. A definite comparison is the fact that with methyl cellulose such may be used in sufiicient quantity at A.;# per 1000 sq. ft. of surface. For comparable results as to I the tough film and continuity, the experience even for months, and with evaporation as to the undercoating limited to thruthe wall body, even when such wall be fiber, it is very materially retarded, and may be further slowed down by a waterproofing coating on the converse or outer side of a fiberboard wall. The characteristic of fluidity in applying the undercoating due to am' monium carbonate, may be in some measure taken care of by other carbonate, especially of the alkali type as sodium or potassium. In the selection of ingredients or materials, costs, as to efficiency, are factors controlling.

The course adopted by applicant has shown advantages in compensating for, or rather permitting volatilizatiom or some vapor escape. In those instances where the container is to take a charge as hot filled; that is, above the boiling point of water, as say hot asphalt at 300 F., entraining or trapping of the vapors would tend to produce blisters at or in the wall and foaming or voids in the contents. Herein, the starch and methyl cellulose or other solution of the overcoating film or skin, tends to pass off at the high temperature. This it is freeto. do thru the porous clay body of the undercoating. The undercoating adhesive is of such minor proportion as not to fill or seal the pores of the fiberboard. Accordingly, the vapors generated by the hot asphalt do not come back into the asphalt, but thru and from the clay body pass into, thru and from the fiberboard outer side, at a rate to avoid bubbling or foaming of the asphalt, and still so distributed in the fineness of exit ways as not to weaken the container wall. Flow of the asphalt is not to contact the wall inner side, for there is the inert clay barrier or wall.

With the container charged with the congealing asphalt, there is the physical strength of the fiberboard wall sufficient, at least at this setting stage for the contents, to hold the clay as a sort of partition or barrier between the asphalt asphalt fOr SllCll gauge of fiberboard. In such instance the clay may run from 51;: to '7# per 1000 sq. ft. and the starch-methyl cellulose l i tper 1000 sq. ft. in which the latter film coat is 60% methyl cellulose. used successfully with 5# of clay per 1000 sq. ft. forthe undercoating and /2# starch-methyl cellulose for 1000 sq. ft. for the overcoating. With the'hot asp-halt acting to vaporize or destroy the film and adhesives of the character of gum or .glue, there remains the undercoating relativelyinertclay body as the barrier. In this embodiment, the absence of a moistureor water vapor barrier, efilciently permits a sort of vapor breathing to avoid any entrapment .01" void cluster regions. to be ready flowing mixtures or solutions, with entire absence of tacky or jelling characteristics. v

From the foregoing, the subject-matter disclosed herein relates to a container wall'comprising an outer layer of fibrous material and an inner dual coating layer impermeable to asphaltum, bonded to but severable from said fibrous layer, said inner dual coating layer comprising a first major body undercoating of water-dispersed clay and sufiicient adhesive that this first undercoating may isolate the second coating from the Wall,

and said second continuous lesser-body-carrying coating agent thereon of organic resin-like material, independent of emulsion with water, possessing a, characteristic for thin film spreading in di rect water solution over the less thin first undercoating and with such cohesive consistency to ganic resin-like material of the second lesserbody-carrying coating.

and the fiberboard, even should the film have It is to be noted that'the coatings as efiective to retain asphalt and the like, have oil proof and grease proof resistant qualities. However, due

to the use of water suspensions and solutions for I carrier or spreadability traits in applying, there is some slight moisture present. The film and wall tend to slow up drying out. Somewhat difierent rate is developed when hot charge of contents be introduced into the container. This speeded up drying out is a sort of exhaling from the container wall.

This application is a continuation-in-part of myPatent 2,333,023 for Container wall.

What is claimed and it is desired to secure by Letters Patent is:

A container wall comprising an outer layer of fibrous material and an inner dual coating layer impermeable to asphaltum, bonded to but severable from said fibrous layer, said inner dual coating layer comprising a first major body undercoating of water-dispersed clay and sufficient adhesive that this first undercoating may isolate thesecond coating from the wall, and said second continuous lesser-body-carrying coating agent thereon of organic resin-like material of methyl cellulose and starch, possessing a characteristic for thin film spreading in direct water solution when applied over the less thin first undercoating.

, WILLARD O. MANOR.

The proportion has been The coatings as applied are of fluidity- 

